Takayuki Ogi

Isolation of C11 Cyclopentenones from Two Didemnid Species, Lissoclinum sp. and Diplosoma sp.

A series of new C11 cyclopentenones 1–7 was isolated, together with four known metabolites 9/10, 12 and 13, from the extract of the didemnid ascidian Lissoclinum sp. The other didemnid ascidian Diplosoma sp. contained didemnenones 1, 2 and 5, and five known metabolites 8–12. The structures of 1–7 were elucidated by spectroscopic analyses. Cytotoxicity of the isolated compounds was evaluated against three human cancer cell lines (HCT116, A431 and A549).

Antioxidant capacity of betacyanins as radical scavengers for peroxyl radical and nitric oxide.

This study was designed to assess the antioxidant capacity of betacyanins as indole derived plant pigments, such as betanin, phyllocactin and betanidin. The antioxidant capacity of the betacyanins was evaluated as an index of radical scavenging ability using the peroxyl radical generating system in the presence of AAPH and NO generating system using NOR3 as an NO donor. The peroxyl radical scavenging capacity was dose-dependent in the low concentration range (25-100 nM). The mol-Trolox equivalent activity/mol compound (mol-TEA/mol-compound) as an index of the antioxidant capacity indicated the following order at 10.70 ± 0.01, 3.31 ± 0.14 and 2.83 ± 0.01 mol-TEA/mol-compound for betanidin, betanin and phyllocactin, respectively. In addition, betacyanins reduced the nitrite-level in the low concentration range of 2.5-20 μM. The IC₅₀ values (μM) of nitrogen radical scavenging activity were 24.48, 17.51 and 6.81 for betanin, phyllocactin and betanidin. ESR studies provided evidence that the compounds directly scavenged NO. These results indicated that betacyanins have a strong antioxidant capacity, particularly betanidin with a catechol group had higher activity than those of the glycoside of betacyanins. This study demonstrated that the betacyanins will be useful as natural pigments to provide defence against oxidative stress.

Cytotoxic Metabolites from the Okinawan Ascidian Diplosoma virens

The unstable isomeric compounds 5-hydroxy-7-prop-2-en-(E)-ylidene-7,7a-dihydro-2H-cyclopenta[b]pyran-6-one (1) and 5-hydroxy-7-prop-2-en-(Z)-ylidene-7,7a-dihydro-2H-cyclopenta[b]pyran-6-one (2), previously described as antimicrobial metabolites from the sponge Ulosa sp., were isolated and identified as major components of the ascidian Diplosoma virens. In this paper, full spectral data for 2 and complete 13C-NMR data for 1, based on 2D NMR measurements, are provided for the first time. Compounds 1 and 2 showed cytotoxity against HCT116 cells (human colorectal cancer cells) by triggering apoptotic cell death.

Isolation of C11 Compounds and a Cyclopropane Fatty Acid from an Okinawan Ascidian, Diplosoma sp.

Pentylphenols 1 and 2, cyclopropane fatty acid 3, and cyclopentenones 4 and 5, were isolated from an ascidian, Diplosoma sp. The structures of 1−5 were determined by spectroscopic analysis and/or synthesis. Compound 1 inhibited the division of fertilized sea urchin eggs and compound 4 showed mild cytotoxity against HCT116 cells (human colorectal cancer cell).

Suppression of nitric oxide production on LPS/IFN-γ-stimulated RAW264.7 macrophages by a novel catechin, pilosanol N, from Agrimonia pilosa Ledeb.

A novel catechin, pilosanol N (1), was isolated from Agrimonia pilosa Ledeb and its structure was determined by (1)H, (13)C NMR and HRESI-MS analyses. Compound 1 inhibited nitric oxide (NO) production in LPS/IFN-γ -induced RAW264.7 macrophages, and then the iNOS gene expression and its protein production with LPS/IFN-γ treatment cells were also suppressed in the presence of 1. In addition, compound 1 scavenged NO or nitrogen radicals generated from NOR3 (4-ethyl-2-hydroxyamino-5-nitro-3-hexenamide) as an NO donor. These results indicated that pilosanol N can decrease the level of NO through a mechanism that involved both a decrease in the NO production and NO scavenging.

Cytotoxic haterumadienone congeners from the Okinawan marine sponge Dysidea sp.

20-Hydroxyhaterumadienone (1) and haterumadienelactol (2), new haterumadienone (3) congeners, were isolated from the sponge Dysidea sp. together with puupehenone (6) and three known metabolites (7-9) related to 6. The absolute stereochemistry of 1 and the relative stereochemistry of 2 were determined by spectroscopic and chemical analyses. The metabolites (1 and 2) inhibited the division of fertilized sea urchin eggs.